Issue #16993 has been updated by Dan0042 (Daniel DeLorme). I like the concept but I'm going to bikeshed the naming: by itself "key_set" is unclear if you don't already know what it does. It sounds like the purpose is to set a key (like instance_variable_set). I'd prefer something a bit more descriptive like "keys_to_set" ---------------------------------------- Feature #16993: Sets: from hash keys using Hash#key_set https://bugs.ruby-lang.org/issues/16993#change-111984 * Author: marcandre (Marc-Andre Lafortune) * Status: Open ---------------------------------------- To create a set from hash keys currently implies a temporary array for all keys, rehashing all those keys and rebuilding a hash. Instead, the hash could be copied and its values set to `true`. ```ruby h = {a: 1} # Now: Set.new(h.keys) # => Set[:a] # After h.key_set # => Set[:a], efficiently. ``` -- https://bugs.ruby-lang.org/